DC says "USADA doesn't catch people all the time," that means, you too DC could be on steroids, and you are one of the people USADA has yet to catch. So, should we just believe that DC is hollier than everybody, and take his word that he is not cheating?
That is stupid. Either USADA is doing a great job, and 95% of cheaters are getting caught, and we can can say with 95% confidence that most fighters who are testing negative are negative or USADA is not doing a good job, and fighters (including DC) are getting away with cheating.
You can't have it both ways.